Abstract
The vitamin C requirement was determined on 2 male adults who were hospitalized during the study and fed diets containing constant minimal amounts of vitamin C. The 24-hour urinary excretion of vitamin C was determined daily and the plasma concentration 3 times a week. The determination of vitamin C in both plasma and urine was done by the indophenol titration method 1 in the first case and in the second case both by titration and by the photoelectric colorimeter. 2 , 3 The use of the photoelectric colorimeter reduces the error due to the small amount of non-vitamin C reducing substances present in the urine. On the diet fed, titration gave urine figures which were consistently higher by 10 mg per day. No significant differences were found in the plasma values.
The first case, L. R., age 57, height 72.5 in., weight 160 lb., was observed for a total of 110 days. In the first period of 19 days he received 50 mg of ascorbic acid daily; during the second period of 53 days he received 100 mg of ascorbic acid daily; during the third period of 22 days, 200 mg daily and during the fourth period of 16 days 350 mg daily. The ascorbic acid was given in divided doses of 50 mg each at regular intervals throughout the day. In the first period the daily excretion of vitamin C averaged 11 mg, the daily retention averaged 39 mg and the blood plasma concentration varied from 0.76 to 0.97 mg %, the average being 0.85 mg %. In the second period the daily excretion averaged 20 mg, the daily retention 80 mg, and the plasma vitamin C varied from 0.93 mg % to 1.22 mg %, the average being 1.12 mg %.
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